The present invention relates generally to methods and apparatus for magnetron sputtering of thin films. In particular, the present invention relates to thin films in heads for use in a magnetic storage drive.
A read/write head in a disc drive typically includes a magnetoresistive (MR) read transducer that is deposited between non-magnetic layers and magnetic shield layers. The magnetoresistive read transducer typically includes a magnetoresistor, electrical contacts and a stack of various layers that have different shapes and compositions depending on the design of the magnetoresistive (MR) read transducer. There is a need to control thickness of the various layers to optimize performance of the read transducer.
One type of magnetoresistive read transducer is a spin valve transducer that include a giant magnetoresistor (GMR). A spin valve transducer typically includes a free layer comprising nickel and iron (NiFe), a spacer layer comprising copper (Cu), a pinned layer comprising cobalt (Co), and an exchange layer comprising iron and manganese (FeMn).
Magnetron sputtering can be used to form layers in a magnetoresistive transducer, in particular, the spacer layer comprising copper in the spin valve transducer. A transducer substrate is arranged in a sputtering chamber generally aligned with a xe2x80x9cracetrackxe2x80x9d pattern defined by a region where the magnetron""s magnetic field intersects with an electric field in front of a sputtering target.
The thickness of resulting thin films on the transducer substrate is most uniform only in a relatively small diameter region, compared to the diameter of the racetrack, and centered along the rotation axis of the magnetron. When a new, uneroded target is used, variations of uniformity of the sputtered film thickness on the order of 6-8% are seen across the wafer substrate or wafer. Better uniformity of the sputtered film thickness is needed, and productions yields are low. The uniformity deteriorates rapidly as the target wears, and targets are replaced frequently in an effort to maintain adequate production yields.
A method and apparatus are needed to improve magnetron-sputtered film uniformity in thin film transducers.
Disclosed is a magnetron sputtering apparatus and a method of manufacturing arrays of magnetoresistive transducers by magnetron sputtering.
A sputtering chamber includes a sputtering target with a front target surface, and a magnetron behind the sputtering target. The magnetron provides a magnetic field at the front target surface along a generally round path that includes a path indentation.
A shutter is spaced apart from the front target surface by a shutter spacing. A substrate is aligned in front of the front target surface and spaced apart from the front target surface by a selected spacing that is greater than the shutter spacing.
A central region on the substrate has a diameter defined by a uniformly sputtered thickness of deposited layers on the substrate. The path indentation is set to a path indentation depth that adjusts the selected spacing to maximize the diameter.
These and various other features as well as advantages that characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.